Metallocene polypropylene crystallization kinetic during cooling in rotational molding thermal condition

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. ABSTRACT: This article is part of an ambitious project. The aim is to simulate mechanical properties of rotomolded part from microstructure consideration. Main objective here is to consider metallocene polypropylene crystallization kinetic (PP) during cooling stage in rotational molding. Crystallization kinetic of metallocene PP is so rapid that microscopy cannot help to observe nucleation and growth. Crystallization rate can be estimated by a global kinetic. Given that cooling in rotational molding is dynamic with a constant rate, Ozawa law appears more appropriate. Ozawa parameters have been estimated by differential scanning calorimetry. In rotational molding thermal condition, Avrami index identifies a complex nucleation intermediate between spontaneous and sporadic. Ozawa rate constant is 68 times higher than this obtained for Ziegler-Natta PP. By coupling transformation rate from Ozawa model and a thermal model developed earlier, the difference between theory and experimental is less than 1%. To optimize rotational molding, study has been completed by sensitivity to adjustable parameters.

Rotational molding: A review of the models and materials

“…However, taking into consideration that SS catalysts are suitable only for olefin polymerization; it is clear that these materials contribute minimally. Different grades of PE [24,[97][98][99][100][101] and PP [102] have, nonetheless, demonstrated their suitability to the RM process. For instance, experiments by Xin et al [98] and later by Hay et al [97] showed that under similar molding conditions SS PEs possessed; better mechanical properties, wider processing windows and higher bubble dissolution rates at lower temperatures than ZN catalyzed polymers.…”

Phosphorous antioxidants against polypropylene thermal degradation during rotational molding‐kinetic modeling

“…A previous article described a thermal model (1D) that simulates evolution of polymer temperature during processing. This model was based on finite differences method using a centered implicit scheme for space and a decentred implicit scheme for time.…”

“…Equations and interfaces were treated with the same system. Calculated results from this thermal model were computed using Matlab with the assumptions described before …”

“…Indirectly, it reflects polymer state changes during processing. To optimize rotational molding, some authors developed models to simulate Tt diagram. Today, the latest model correctly predicts Tt diagram with an error <1% between theory and experiment .…”

“…To optimize rotational molding, some authors developed models to simulate Tt diagram. Today, the latest model correctly predicts Tt diagram with an error <1% between theory and experiment . Thermal and chemical models were also coupled to describe PP thermal oxidation during processing by rotational molding .…”